Safe, sane and consensual are our maxims in this life and no matter how experienced you are, or how gentle the play is safewords should be part of your negotiations before commencing any type of play. Special consideration should be made if you are to use any form of gag, blindfold or bondage.
May I also say how important safewords are for the Dominant as well as the slave. I personally would advise anyone who plays with a partner who says they do not use safewords to run a mile, or to at least insist and discuss the reasons why.